In recent years, a field effect transistor (FET) having a gate electrode disposed between a source electrode into which a current flows and a drain electrode from which it flows out for controlling the current (drain current) between source/drain by a voltage applied to the gate electrode has been proposed. The field effect transistor includes an MOS type (MOSFET) having a MOS structure fir the gate and a junction type using a pn junction or a Schottky junction.
In MOSFET having the MOS structure for the gate electrode, the conductivity of a channel region through which the drain current flows is controlled by utilizing that an inversion layer due to minor carriers is formed on the surface of a semiconductor. Then, since the current value changes when a gate voltage is changed, it can function for amplification of electric signals or as a current on/off switch.
As described above, the semiconductor device having the MOS structure for the gate includes a silicon carbide semiconductor device (MOSFET) using a semiconductor including silicon carbide (refer, for example, to Japanese Patent No. 3307184).